More video

Believers make one at home or plunk down $8 a bottle, hoping a juice cleanse will detoxify their body and perhaps help them lose weight.

With celebrity backing, cleanses have blossomed into a $5 billion industry. Consumers say drinking them makes them feel great, although experts warn there is no proof they work and can even be dangerous, according to a report on TODAY Monday.

In his Los Angeles kitchen, Martin Muoto makes his own version of the Master Cleanse. For 10 days, he swaps solid food for a mix of water, lemon juice, cayenne pepper and agave.

“The first three days are the toughest in the Master Cleanse. That’s when you’re most hungry,” Muoto said in the TODAY segment. “If you can get beyond three days, you feel the toxins just seeping out of your body.”

As he progresses, Muoto says: “You feel fantastic. You have more energy. You sleep better and you go through what is almost a spiritual experience.”

Experts, though, say there is no scientific evidence the products remove toxins in the body, a function handled by the liver and kidneys. And they warn that people subsisting solely on the cleanses are not getting proper nutrition.

“The basic problem is this is an unbalanced diet approach,” Dr. David Heber, an endocrinologist at UCLA, told TODAY. “There’s no way that a three-day detox diet is going to remove toxins that you may or may not have in your body.”

A short cleanse may not be harmful, however, he said. “Maybe a day or two or three as kind of a jump-start to a diet, because mentally, it’s sort of like throwing down a package of cigarettes,” Heber added.

A TODAY.com survey of several hundred people found that 60 percent had not tried a cleanse, while 40 percent had. Of those who had used a cleanse, the majority, 61 percent, said they felt better afterward, with 7 percent saying they felt worse and 32 percent feeling no different.

TODAY contributor Dr. Roshini Raj was not surprised that so many people indicated they had tried the cleansing products, saying a lot of her patients ask about them.

“Everyone wants to lose weight. They want to feel healthy and they think this might be an option,” Raj told TODAY’s Willie Geist. “If you find yourself even thinking about a cleanse, it’s probably a sign that in general you’re not happy with the way you’re eating and you might want to talk to someone about a balanced approach that's a more long-term solution.”

Raj, a gastroenterologist at NYU Langone Medical Center in New York, warned that cleanses are potentially dangerous, especially for people with medical conditions or those taking medication, along with pregnant women and the elderly.

“Some of the cleanses are very extreme and they incorporate only very few ingredients in them, so you’re really limiting yourself in terms of not getting enough protein, potentially not enough fiber and even healthy fats that you need,” Raj said.

People who cleanse are unlikely to maintain any weight loss, she said.

“It’s very temporary water weight that you’re losing so it’s not going to persist,” Raj said. “You’re going to eat more later because you’re hungrier. It’s just not a balanced approach to weight loss, and this notion that you can sort of eat whatever you want and then cleanse for a week and get rid of all the bad effects from the prior poor eating just doesn’t make sense.”

“You want to, of course, eat a lot of fruits and vegetables,” she added, “but have a balanced diet and you need a long-term plan, not just a three-day or a six-day cleanse.”

Raj offered warnings on three types of cleanses.

The juice cleanse, she said, purports to help with the immune system and to detoxify the body.

“The truth is, you’re just getting a lot of fruits and vegetables, which is a good thing, but to the exclusion of everything else, not so great,” Raj said, adding that many of the juice products have a lot of sugar. “I don’t mind having a juice drink instead of one meal, but when it’s three meals for several days, it’s not a good idea.”

She said the drawback of adding herbal supplements to a cleanse is that you do not know how they will react in your body or with medication are taking. A cleanse made only of raw fruits and vegetables is too limiting for the body, she said.